A thread cutter called “seam ripper” is known as a tool to rip stitches. An example of such a seam ripper is disclosed in Japanese Design Registration No. 1201385. As disclosed therein, a typical seam ripper may include an elongated metal member coupled to a handle to be held by a user, and the metal member has, at its tip, a cutting blade flanked by a needle portion and a ball-shaped portion that provide a fork-like shape. In use, for example, the needle portion is inserted into a seam, and the seam ripper is pushed forward so that the cutting blade will cut the thread of the seam. The conventional seam ripper comes with a protective cap configured to cover the metal member (in particular, the cutting blade and the needle portion) when the ripper is not in use.
JP-U-S52-81340 discloses a seam ripper whose elongated metal member (with a fork-like end including a cutting blade) retractable into a handle. In this conventional seam ripper, the metal member is configured to slide into or out of the inner space of the handle by a screw mechanism. To use the seam ripper, the user rotates the operating portion of the handle, causing the blade part to come out gradually from the inside of the handle due to the screw mechanism. After the work with the ripper has been done, the user can bring the whole of the metal member back into the handle by rotating the operation portion in the opposite direction. Advantageously, such a configuration eliminates the need for preparation of an additional protective cap to cover the blade part.